The project is designed to define the molecular events subserving the structural and functional changes in the CNS of developing thyroid hormone-deficient rats. One particular facet of this problem is the study of the developmental increase in microtubular protein and the documentation of some of the properties such as half-life of colchicine- binding, molecular weight, synthesis and turnover rate. A second aspect under investigation is the synthesis and turnover of cerebral gangliosides and glycoproteins which along with microtubular protein are important structural and functional elements of nerve processes. The pattern of incorporation in vivo of labelled glucosamine into cerebral cortical gangliosides and glycoproteins and the distribution of the radioactivity among individual gangliosides is presently under investigation.